摘要
结合状态方程建立晶体塑性有限元模型,模拟高速冲击加载条件下<100> LiF的动态弹塑性大变形行为,得到应力波剖面特征、动态力学演化规律及其连续介质力学根源。结果表明:毫米级样品经约15 GPa以内的低压冲击,波剖面具有弹塑性双波响应、弹性前驱衰减和应力松弛现象,其决定性因素包括样品厚度、外加压力和材料本构;从连续介质力学角度分析得到,应力松弛本质上是由于黏性塑性流动,导致总应变增速小于塑性应变增速,从而使弹性应变减小、压力降低;提出用压力关于时间的三阶导数大于零作为判断条件,对应力波剖面上双波和单波响应的临界压力进行估测,发现随着样品掺杂浓度的增加,临界压力增大;高速冲击变形的温升效应不可忽略,且温升绝大部分来自弹性体积变形的贡献。
A crystal plasticity finite element model combined with equation of state was built to simulate the dynamic elastic-plastic large deformation behavior of <100> LiF under high-rate shock loading.The characterization of the stress wave profile,the patterns of the dynamic mechanical evolution and their essential causes in view of the continuum mechanics were obtained through simulations,with the following results achieved:(1)the wave profiles of millimeter-sized specimens exhibit elastic-plastic two-wave response,elastic precursor decay and stress relaxation below 15 GPa;(2)in view of continuum mechanics,the stress relaxation is essentially due to the viscous plastic flow which accounts for the increase rate of the total strain being less than that of the plastic strain,and which further reduces the elastic strain and pressure;(3)the third derivative of pressure to time being greater than zero was proposed as a criterion for estimating the critical pressure of the two-wave and the one-wave response of the stress wave profile,and the estimation result indicated that the critical pressure increased with the increase of the doping concentration in specimen;(4)the effect of temperature rise during the high-rate shock deformation is non-negligible,and the elastic volumetric deformation contributes to most of the temperature rise.
作者
刘静楠
叶常青
陈开果
俞宇颖
沈耀
LIU Jingnan;YE Changqing;CHEN Kaiguo;YU Yuying;SHEN Yao(The State Key Lab of Metal Matrix Composites,School of Material Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;National Key Laboratory of Shock Wave and Detonation Physics,Institute of Fluid Physics,CAEP,Mianyang 621999,China)
出处
《高压物理学报》
EI
CAS
CSCD
北大核心
2019年第1期49-60,共12页
Chinese Journal of High Pressure Physics
基金
科学挑战专题(TZ2018001)
关键词
LIF
晶体塑性
状态方程
应力松弛
双波响应
LiF
crystal plasticity
equation of state
stress relaxation
two-wave response
